Chronic neuropathic pain (NP) is a widespread condition that is often associated with diabetes, cancer, injury, exposure to toxic substances and a variety of other diseases such as AIDS and Parkinson's disease (Renfrey, S. et al., Nat. Rev. Drug Discov. 2003, 2: 175-6; Farquhar-Smith, P., Curr. Opin. Support Palliat. Care 2011, 5: 1-7). When it occurs subsequent to cancer chemotherapy or radiation therapy, it often necessitates the discontinuation of a life-saving treatment. Currently-used therapies for NP are poorly efficacious and suffer from serious side effects, ranging from liver toxicity to addiction and personality changes. In many cases, the therapy involves drugs developed for a different condition that were incidentally found to reduce NP, e.g. biogenic amine reuptake inhibitors such as the antidepressant amitriptyline, or anticonvulsant drugs such as gabapentin. Opioids, which are effective against acute pain, are not the first line of treatment for chronic NP, both because of addiction liability, low efficacy, development of antinociceptive tolerance and hypersensitivities to thermal, cold and mechanical insults (Ossipov, M. H. et al., J. Neubiol. 2004, 61: 126-48). Thus, there is an unmet need for chronic neuropathic pain treatment that operates on a different mechanism that can be given as stand alone or as adjuncts to opioids to allow effective pain relief over chronic use without engaging dependence.